Is This Year’s El Niño Set to Become the Strongest Ever Recorded?
El Niño is on track to reach an intensity never before documented in modern recorded history. Characterized by far warmer-than-average sea surface temperatures across the equatorial Pacific, this cyclic climate event occurs every few years, and meteorological agencies and climate researchers across the globe are already on high alert. When massive amounts of heat stored in the Pacific Ocean release into the atmosphere, it sets off a global chain reaction that reshapes rainfall patterns, shifts average temperatures, and alters hurricane activity around the world.
This year’s El Niño has intensified at an extraordinary rate, and its ripple effects will touch every sector from commercial fisheries to alpine ski seasons across multiple continents. While not all outcomes are negative—the chronically parched U.S. Southwest, for example, is likely to see above-average winter precipitation—anticipating these shifts is the key to effective preparation. Below, we break down what is unfolding right now, what we can expect in the coming months, why this event could qualify as a historic super El Niño, and where impacts will be felt most acutely.
What Is El Niño?
Officially classifying an El Niño event requires meeting a specific threshold for ocean warming in the Pacific, centered on a key monitoring zone called Niño 3.4. For those interested in the finer details, this region sits between two smaller monitoring zones (Niño 3 and Niño 4) in the east-central tropical Pacific.
The U.S. National Oceanic and Atmospheric Administration (NOAA) uses the three-month average sea surface temperature of Niño 3.4 to determine if an El Niño is active. If temperatures stay 0.5 degrees Celsius (0.9 degrees Fahrenheit) above the long-term baseline across three overlapping three-month periods, the event is officially declared an El Niño. Other global weather agencies use slightly different frameworks: Japan’s Meteorological Agency monitors a slightly adjusted geographic region with its own criteria, while the Australian Bureau of Meteorology includes an atmospheric component in its threshold for declaration.
Beyond warmer ocean waters, El Niño also weakens the east-to-west blowing trade winds that normally push warm water toward Asia and Australia. Without that consistent westward push, warm surface water piles up along the eastern side of the Pacific instead. During the strongest El Niño events on record in 1997 and 2015, regional sea levels rose more than 18 centimeters (7 inches) above the long-term average.
All this large-scale shifting increases the probability of dramatic weather changes across the globe: increased rainfall in the U.S. Southwest, drier conditions in the Pacific Northwest, a milder, less active Atlantic hurricane season, higher drought risk for Indonesia and parts of southern Africa, and increased odds of warmer-than-average winters across Japan, parts of Australia, and Brazil. It is important to note that these are probabilistic shifts, not guarantees—El Niño is not the only factor shaping day-to-day or seasonal weather, but it consistently tilts the odds toward these outcomes.
What Is a Super El Niño?
“Super El Niño” is not an official term used by any major meteorological agency, but scientists generally use the label to describe any El Niño event where Niño 3.4 temperatures rise at least 2 degrees Celsius above the long-term average. While no formal standardized definition exists, four El Niño events are widely recognized as meeting the super El Niño criteria: 1982–83, 1997–98, 2015–16, and the ongoing 2023–24 event.
Even seemingly beneficial impacts of El Niño can turn destructive during super events. During the 1982–83 super El Niño, for example, the U.S. Colorado River Basin saw record-breaking heavy snowfall. When combined with unusually high spring temperatures and added rainfall, the river’s total flow hit 1.5 times the long-term average. Upstream reservoirs filled to capacity one after another, forcing emergency water releases, and Lake Mead reached near-full capacity, leading water to overflow the Hoover Dam spillway for the first time in roughly 40 years. The event left the basin with extensive flood damage, proving that even “positive” El Niño shifts can lead to severe negative outcomes.
In 1997–98, super El Niño conditions drove the worst drought Indonesia had seen in half a century, while the 2023–24 super El Niño contributed to the worst drought southern Africa has faced in more than 100 years. Conditions were so extreme that approximately 61 million people across the region required emergency humanitarian aid.
How Is This Year’s El Niño Shaping Up?
NOAA projects there is a greater than 90% probability that this El Niño will reach “very strong” intensity during the Northern Hemisphere fall and winter. Modeling run by independent climate research group Berkeley Earth finds the median projected sea surface temperature anomaly for the Niño 3.4 region could reach 3.6 degrees Celsius above the pre-industrial baseline—even after accounting for the warming effect of long-term global climate change.
This would beat the previous all-time record set during the 2015–16 El Niño by roughly 0.8 degrees Celsius. To put that gap in context: the difference between the strongest and fifth-strongest El Niño events of the past 150 years is only around 0.5 degrees Celsius, making this level of warming truly exceptional.
This El Niño is also developing far faster than the typical event. While the 2015 El Niño formed when sea surface temperatures were already rising above average, this year’s event emerged from a La Niña state, where Pacific sea surface temperatures were below average. Even so, it is intensifying faster than the 1997–98 super El Niño, one of the fastest-growing major events on record.
The far-reaching economic impact of major El Niños also cannot be overlooked: one analysis found the 1997–98 super El Niño caused a cumulative $5.7 trillion in global economic losses over the five years following the event.
What About La Niña?
La Niña is El Niño’s opposite counterpart, defined by cooler-than-average sea surface temperatures across the equatorial Pacific. Like El Niño, it occurs every few years, and its global impacts are generally the reverse of El Niño’s: it increases the odds of wetter conditions in Indonesia, a more active Atlantic hurricane season, and drier conditions in the U.S. Southwest, among other shifts.
That said, current projections indicate El Niño will remain the dominant global climate pattern until at least next spring, so La Niña’s impacts are not a major concern for the coming months.
This article was originally published in WIRED Japan and adapted from the original Japanese version.
